How to Use the GetDiskFreeSpace API Call

• Microsoft Visual FoxPro for Windows, version 3.0

SUMMARY

By using the GetDiskFreeSpace API call, you can determine how much disk space a drive has, how much is used, and how much is free. This article explains how to use and call the Win32 GetDiskFreeSpace API.

MORE INFORMATION

In many cases, such as backing up or restoring user data, you need to know various characteristics about the media with which you are working (such as whether or not it is fixed or removable) and about the amount of available space on that media.

By using the GetDiskFreeSpace API call, you can derive the low-level information about the disk (such as bytes per sector and sectors per cluster), and then use that information for your calculations.

The following code demonstrates the syntax and use of this API call and gives some of the more common calculations you may need to perform.

Code Sample

**---------------------------------------------------------------**

** Program: Getspace.prg                                         **
** Purpose: Demonstrates how to declare and call the Win32       **
**          GetDiskFreeSpace API.                               **

        lpSectsPerCluster, ;
        lpBytesPerSector, ;
        lpNumberOfFreeClusters, ;
        lpTotalNumberOfClusters

lpRootPathName       = "A:\"
lpSectsPerCluster    = 0
lpBytesPerSect       = 0

lpTotNumOfClusters   = 0

        STRING  @lpRootPathName, ;
        INTEGER @lpSectsPerCluster, ;
        INTEGER @lpBytesPerSect, ;
        INTEGER @lpNumOfFreeClusters, ;
        INTEGER @lpTotNumOfClusters

        @lpNumOfFreeClusters, @lpTotNumOfClusters)

        FLOAT CLOSE ;
        TITLES "Drive Information for " + ;
        ALLTRIM(lpRootPathName) ;
        FONT "Courier",10

@ 0,1 SAY "Drive & path name            : " + ;
   ALLTRIM(lpRootPathName)
@ 1,1 SAY "Sectors per cluster          : " + ;
   ALLTRIM(STR(lpSectsPerCluster))
@ 2,1 SAY "Bytes per Sector             : " + ;
   ALLTRIM(STR(lpBytesPerSect))
@ 3,1 SAY "Number of free clusters      : " + ;
   ALLTRIM(STR(lpNumOfFreeClusters))
@ 4,1 SAY "Total number of clusters     : " + ;
   ALLTRIM(STR(lpTotNumOfClusters))

@ 6,1 SAY "Total disk space             : " + ;
   ALLTRIM(STR(lpSectsPerCluster * lpBytesPerSect * lpTotNumOfClusters))
@ 7,1 SAY "Free disk space              : " + ;
   ALLTRIM(STR(lpSectsPerCluster * lpBytesPerSect * lpNumOfFreeClusters))
@ 8,1 SAY "Used disk space              : " + ;
   ALLTRIM(STR(lpSectsPerCluster * lpBytesPerSect * ;
   (lpTotNumOfClusters - lpNumOfFreeClusters)))

When this code is run on a 1.44-megabyte floppy disk, the following output is what you would get if the floppy disk is a new, formatted floppy disk that contains no data:

Drive & path name        : A:\
Sectors per cluster      : 1
Bytes per sector         : 512

Total disk space         : 1457664
Free disk space          : 1457664
Used disk space          : 0

For additional information on this API function, please see the "GetDiskFreeSpace" topic in the Win32API help file. Note that this help file is available only on the compact disc version of Visual FoxPro; it is not shipped with the disk version. For more information, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q139172
   TITLE     : PRB: Visual FoxPro CD-ROM Compact Disc Includes Extra Files